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Sunday, November 25, 2012

SpaceX engine probe delays Jan. flight

SpaceX has delivered a Falcon 9 rocket to Cape Canaveral while continuing an engine-problem investigation that will delay the booster’s planned launch from mid-January to early March. Company and NASA engineers are still sorting out what caused one of nine Merlin engines to shut down early during the Oct. 7 launch of a Dragon cargo capsule to the International Space Station, NASA officials told an advisory committee.

The NASA Advisory Council’s Human Exploration and Operations Committee also learned at its Nov. 14 meeting about several anomalies the Dragon spacecraft experienced during its first commercial resupply mission to the station.

But Mike Suffredini, NASA’s ISS program manager, said last month that the outpost is well-stocked, and there is no urgency to fly the next Dragon mission, the second of 12 under a $1.6 billion contract.

“We’re in really good shape on orbit, so we could move quite a bit to the right and not really be impacted by it,” he said during a news conference Oct. 26. “So we’ve got plenty of time to sort out root cause. The team is doing an excellent job.”

A commercial satellite flown as a secondary payload, however, was left in a lower-than-desired orbit and re-entered the atmosphere within days.

Debris blew away from the rocket when the engine suddenly lost pressure. That was not an explosion, SpaceX said, but likely a release of pressure that shattered an aerodynamic shell around the engine.

Among the anomalies the Dragon encountered during the mission:

• Loss of the use of a flight computer because of a suspected radiation hit knocking it out of sync with the two others. SpaceX said it offered to re-sync the computers but NASA determined that was unnecessary.

“With two nominally performing computers, we still had redundancy as Dragon needs only one computer to fly,” SpaceX spokeswoman Katherine Nelson said in an email.

• One of three GPS units, and several other components, also were recovered after suspected radiation hits, events Nelson said had “no impact on the mission.”

• Failure of three sensors on the spacecraft’s 18 Draco thrusters, none of which violated flight requirements.

• Loss of all three coolant pumps and power to a freezer holding biological samples because of water intrusion after splashdown in the Pacific Ocean on Oct. 28. The freezer temperature was restored several hours later and circulation fans kept the cabin temperature within required levels.

“SpaceX learns from every mission, and new waterproofing methods are already being successfully tested on our avionics for future flights,” said Nelson.

The Dragon slated to fly NASA’s second commercial resupply mission, now tentatively targeted for March 1, is expected to be delivered to the Cape next month.